Air-break low-voltage power circuit breakers require for operation an arc-quenching device in order to cause switching arcs which occur to be quenched without impairing the power circuit breaker itself and adjacent parts of the assembly or other modules. On the other hand, there is the risk of the hot and thus ionized arc gases causing electrical flashovers, injuring operating personnel or causing other damage.
It is known, on the one hand, to provide arcquenching chambers which accommodate the arc to be quenched and are designed for the temperature and pressure of the switching gases occurring. In order in particular applications of low-voltage power circuit breakers, for example when they are installed in tightly restricted areas, to achieve further cooling and final ionization of the switching gases, it is known, in addition to the arc-quenching chamber, to provide a switching gas damper which is arranged in the flow path of the switching gases, downstream of the quenching chamber.
DE 35 41 514 C2 proposes, for this purpose, arranging an attachment on the arc-quenching chamber which accommodates a number of perforated inserts, these inserts being, for example, sheets provided with closely adjacent perforations or sections of a wire fabric.
A similar switching gas damper is known from U.S. Pat. No. 6,248,971 B1, in accordance with which perforated plates are likewise provided.
A further switching gas damper is known from DE 298 07 119 U1. However, instead of the plates or instead of a wire fabric, in this case parallel webs are provided which are arranged such that they are offset.
DE 19 54 066 A has disclosed an arrangement having a low-voltage power circuit breaker and a switching gas damper, which is provided with a bearing element, for the low-voltage power circuit breaker. Here, the switching gas damper is arranged above an open arc-quenching chamber of the low-voltage power circuit breaker and has at least one inlet opening for switching gases and at least one outlet opening for damped or completely ionized switching gases. Further, the bearing element can be fixed on a housing accommodating the low-voltage power circuit breaker above the arc-quenching chamber and forms at least one accommodating area for a flow element which builds up a flow resistance for the switching gases, the bearing element forming the at least one inlet opening. However, the solution is very space-intensive.
A less space-intensive solution is given by EP 0 437 151 A1. In this case, the switching gas damper is arranged on a switchgear cell, which accommodates the power circuit breaker, immediately adjacent to the arc-quenching chamber. The switching gas damper includes an integral housing having openings on its upper side. The housing interior is divided into two regions by means of a perforated plate. Such a design is unfavorable in terms of manufacturing. In addition, the housing interior is only accessible once the entire switching gas damper has been removed from the switchgear assembly.